1. Field of the Invention
The present invention relates to a semiconductor light-emitting device, and more particularly, to a semiconductor light-emitting device with high light-extraction efficiency.
2. Description of the Prior Art
Nowadays, semiconductor light-emitting devices, such as light-emitting diodes, have been used for a variety of applications, e.g., illumination and remote control. To ensure high functional reliability and a low power requirement of the semiconductor light-emitting devices as far as possible, the semiconductor light-emitting devices itself is required for the external quantum efficiency.
In theory, the external quantum efficiency of a semiconductor light-emitting device is determined by the internal quantum efficiency and the light-extraction efficiency of the semiconductor light-emitting device. The internal quantum efficiency is determined by the material property and quality. If the density of the internal defects, such as dislocations, of the semiconductor light-emitting device increases, the internal quantum efficiency of the semiconductor light-emitting device decreases. However, on the condition that the internal quantum efficiency can not be increased efficiently, the importance for the increase of the light-extraction efficiency is emphasized.
The increase of the light-extraction efficiency is for guiding the light emitted from the inside of the semiconductor light-emitting device to the outside of the semiconductor light-emitting device. If the moving direction of the light inside the semiconductor light can be continuously changed to decrease the total reflection probability, the light can be prevent from being limited inside the semiconductor light-emitting device, so as to further increase the light-extraction efficiency of the semiconductor light-emitting device.